Temperature regulating control



Nov. 2, 1965 F. L. LAPORTE 3,214,930

TEMPERATURE REGULATING CONTROL Original Filed June 16. 1960 5Sheets-Sheet 1 COMPRESSOR 24 I {op-f 34 a: w 23 33 2 i nznaasr E? gm/0WFRANCIS LA L/JPOIPTE Isa 35% y Nov. 2, 1965 F. 1.. LAPORTE 3,214,930

TEMPERATURE REGULATING CONTROL Driginal Filed June 16, 1960 .3Sheets-Sheet 2 gnaw/MM FRANCIS L LAPOETE 1 SJ MM Nov. 2, 1965 F. LLAPORTE 3,214,930

TEMPERATURE REGULATING CONTROL Original Filed June 16, 1960 .3Sheets-Sheet 5 grw /MM FRANCIS LA LAPORTE United States Patent Ofi ice3,214,93h Patented Nov. 2, 1965 3,214,930 TEMPERATURE REGULATING CONTRGLFrancis L. Laporte, San Mateo, Calif.; Bernadine L.

Laporte, widow of said Francis L. Laporte, deceased Original applicationJune 16, 196%, Ser. No. 36,61i), now

Patent No. 3,102,315, dated Sept. 3, 1963. Divided and this applicationAug. 26, 1963, Ser. No. 333,779

2 Ciaims. (Cl. 62156) This invention relates to improvements in atemperature regulating control, and more particularly to devices forregulating the flow of heat to a body in accordance with temperatures atvarious portions of the body. This application is a divisionalapplication based on my application Serial No. 36,610, filed June 16,1960, now United States Patent No. 3,102,396.

In a Wide variety of types of apparatus heat is applied to a body orsystem in order to bring the system up to a desired temperature. Heat isoften applied to the system at one point and spreads throughout thesystem to achieve the desired results.

A typical situation may be found in the refrigeration industry inconnection with the defrosting of the evaporator coil. When frost buildsup on such coils, it has an insulating effect reducing the heat transferbetween the coil and the surrounding air. It then becomes necessary toremove the frost from the coil.

Probably the most efiicient method for quickly removing such frost is tosupply heat to the coil either through the coil itself or through aseparate defrosting system. However, certain problems arise incontrolling the length of time during which the heat is applied.

In order to maintain the contents of the refrigerator in chilledcondition, the length of the defrost cycle should be as short aspossible. Thus, the control should act to halt the supply of defrostingheat and resume the refrigcrating process as soon as the coil iscompletely defrosted. In this connection, it should be kept in mind thatthe defrosting should be accomplished over the entire length of thecoil, that is, defrosting should continue until all of the accumulatedfrost has melted and fallen from the coil.

Since the defrosting heat is usually applied to the coil at one endthereof or at spaced locations along the coil, various portions of thecoil will warm up before other portions reach the desired temperature.

In order to obtain effective control of the defrosting cycle it isnecessary that the defrosting heat be supplied to the evaporator coiluntil the coldest parts thereof have become defrosted. A singleheat-responsive thermostatic means would not supply the required controlin refrigerating apparatu wherein the coldest portion of the evaporatorduring the refrigerating cycle is not necessarily the coldest portionduring the defrosting cycle.

For example, defrosting of the evaporator coil is often accomplished byvalve means at the compressor which routes the hot refrigerant throughthe coil. This hot refrigerant often enters the coil at the same end asthe cold refrigerant does during the refrigerating cycle, that is, atthe end of the evaporator coil adjacent to the expansion valve. In suchsystems, during the refrigerating cycle, the intake end of the coil willbe colder than the outlet end and frost will accumulate faster upon theintake end.

Similarly, during the defrosting cycle, the intake end of the coil willheat up and become defrosted faster than the outlet end of the coil.

An ordinary thermostatic means positioned at the intake end of the coilcould therefore initiate the defrosting cycle at the desired time, butcould not positively insure that the discharge end of the coil bedefrosted without extending the defrosting period longer than necessary.

The present invention contemplates a control means which is operative toactuate the defrosting device until the coldest point on the coil hasreached defrosting temperature at which moment the control will cut offthe supply of defrosting heat and again initiate the refrigeraion cycle.This is accomplished by a closed system containing vaporizable fluidconnected to a pressure-responsive actuator which, when pressure issupplied thereto by such system, will operate a switching means adaptedto turn off the defroster and resume the normal supply of refrigerant tothe evaporator coil.

A heat sensing element is mounted locally on the body to cause theVolatile fluid in the system to vaporize when the correct defrostingtemperature has been reached at the coldest part of the coil, and meansis provided for limiting the rise in pressure at the actuator until thisend has been accomplished.

It is therefore, a principal object of the present invention to providea temperature regulating control for a body subject to unevenlydistributed changes in temperature which will respond to such changes intemperature in supplying heating and cooling effects to the body.

Another object of the present invention is to provide a device forcontrolling the refrigeration and defrosting cycles of refrigeratingequipment in accordance with temperature changes at spaced portions ofthe refrigerating system.

A further object of my invention is to provide a temperature regulatingcontrol incorporating a pressure-responsive actuator and a plurality oftemperature-responsive elements mountable in spaced relation on arefrigerator evaporator coil and formed for operating the actuator inresponse to changes of temperature in the coil.

Still another object of the present invention is to provide atemperature regulating control of the character described in whichpressure rise occasioned by warming of one temperature sensitive elementwill be opposed by a pressure-reducing effect at a different temperaturere sponsive element whereby actuation will not occur until pressureconditions are the same at both elements.

Further objects and advantages of my invention will appear as thespecification continues, and the new and useful features of my inventionwill be fully defined in the claims hereto attached.

The preferred forms of my invention are illustrated in the accompanyingdrawings forming part of this application, in which:

FIGURE 1 is a schematic representation of a temperature regulatingcontrol constructed in accordance with with the present invention;

FIGURE 2, a schematic representation of a modified form of thetemperature regulating control of FIGURE 1;

FIGURE 3, a schematic representation of a further modified form of thetemperature regulating control of the present invention;

FIGURE 4, a schematic representation of a fourth form of the invention;

FIGURE 5, a cross-sectional view of a check valve and manuallyadjustable restriction arrangement forming part of the system of FIGURE3 and FIGURE 6, a further modified form of the temperature regulatingcontrol of the present invention.

While I have shown only the preferred forms of my invention, I wish tohave it understood that various changes or modifications may be madewithin the scope of the claims hereto attached, without departing fromthe spirit of the invention.

Referring to the drawings in detail, FIGURE 1 depicts schematically apreferred form of the invention which includes a control means 11 for abody temperature changing device (not shown), a pressure responsiveactuator 12 for the control means 11 and a closed system 13 operativelyconnected to the actuator and containing a fluid 14 adapted to vaporizeabove a predetermined temperature and to condense below saidtemperature, said system being adapted for mounting in heat-transmittingrelation to a body 16 whereby cooling of the body below a predeterminedaverage temperature will condense the fluid 14 and create a low pressurecondition in the system 13, and heating of the body 16 will vaporize thefluid and create a higher pressure condition in the said system.

Incorporated in the system 13 is means for limiting the rise of pressurein the system at the actuator 12 until the entire body 16 has warmed toa predetermined temperature. In the form of the invention illustrated inFIGURE 1, the last-named means is provided by locating portions of thesystem 13 in heat-transmitting relation to spaced sections of the body16 and providing conduits 17 and 18 connecting these portions to theactuator 12 in such manner that vaporized fluid from the warmer of theportions will condense in the colder of the portions until the body 16at the latter portion has warmed to a predetermined temperature.

The control device of FIGURE 1 is particularly suited for use incontrolling the refrigeration and defrosting cycles of an evaporatorcoil, and the associated portions of such a coil are illustrated inphantom lines in FIG URE 1. As here shown, bulb-type reservoirs 19 and20 are formed for mounting in contact with the intake and outlet ends 21and 22, respectively, of a refrigerator evaporator coil 16.

The actuator 12 is here provided by a Sylphon type bellows 23 whichbears against a pivoted arm 24 forming part of the control means 11. Acoil spring 26, having means 27 for adjusting the compression thereof,bears against the opposite side of the arm 24.

The control means 11 here consists of the two-way switch means 28 havingcontacts 29 and 31 connected to leads 32-33, respectively, lead 32 beingadapted for connection to the compressor motor of the refrigeratingsystem (not shown) and lead 33 being adapted for connection to thedefrosting means (also not shown).

Arm 24 is connected by leads 34 to a suitable source of power and isprovided at its distal end with contacts 36 and 37 engageable withswitch contacts 29 and 31, respectively, as the arm 24 moves up and downunder the influence of the actuator 12.

During the refrigerating cycle, the frost will build up faster on theinlet end 21 of the evaporator coil 16 than it will on the remainder ofthe coil. The layer of frost acts as an insulating layer and retards thetransmission of heat from the outside air to the cold refrigerant. Asthe frost layer builds up, the metal of the coil gets colder and colder.

Advantage is taken of this phenomenon to start the defrosting cycle whenthe layer of frost is built up to a predetermined thickness. Since thetemperature of the metal of the coil at the intake end will beproportionate to the layer of frost, the defrosting cycle may be startedwhen the temperature of the metal falls to a predetermined range.

The volatile liquid 14 may be any one of the vaporizable liquidscommonly employed in refrigeration systems. The particular fluid usedwill be determined in part by the operating temperature at which thedefrosting cycle should be started. At such temperature range the fluidshould condense thus creating a low pressure condition in the closedsystem 13.

This will cause the bellows 23 to contract allowing the spring 26 topush the arm 24 downwardly and engage contacts 37 and 31 so as to supplycurrent to the defrosting means. As the hot refrigerant enters the coil16 through the intake end 21, it will warm up the metal of the coil andsoon raise the temperature in the reservoir 19 above the vaporizingtemperature of the fluid 14. The fluid will then vaporize and tend toincrease the pressure in the system 13.

As an important feature of the present invention, rise in pressure atthe actuator 12 suflicient to operate the actuator, is prevented untilthe rest of the coil has also reached the correct defrostingtemperature.

This is accomplished by the reservoir 20 which is located at or near theexit end 22 of the evaporator coil 16. The vaporized fluid will passfrom reservoir 19 and through the conduits 17 and 18 to the reservoir20. So long as the outlet end 22 of the evaporator coil is below thepre-selected defrosting temperature, the vaporized fluid will condensein the reservoir 20, thus tending to reduce pressure in the system 13.This will continue until the exit end, and hence the entire coil, hasreached the desired temperature at which time the fluid 14 in thereservoir 20 will also begin to vaporize.

The vaporized fluid will pass from reservoir 20 through conduit 18 andinto the bellows 23.

As soon as the pressure has risen sufliciently to overcome the action ofspring 26, the arm 24 will be moved upwardly disconnecting thedefrosting means from the power lead 34 and bringing the contacts 36 and29 into engagement to supply power to the compressor motor. This, ofcourse, will re-initiate the refrigeration cycle. A conventional toggleaction (not shown) may be connected to arm 24 so as to cause it to snapfrom one terminal position to the other.

Precise control of the temperature at which the switch means will bemoved to the last-named position by the actuator 12 is here provided bythe adjusting means 27 designed to vary the compression of the Spring26. Increasing compression upon the spring will increase the amount ofpressure required in the actuator to overcome the spring and hence willraise the temperature at which the defrosting apparatus will be shut offand the refrigerating cycle recommenced.

As here shown, the means 27 includes a threaded rod 41, which may besecured to a convenient portion of the apparatus housing and which hasnuts 42 screwed up against the opposite sides of a spring retainer 43 tohold the latter in desired position. It will be understood that anysuitable means for adjust-ing the bias of the spring '26 may be used inplace of the means 27.

In the form of the invention illustrated in FIGURE 2 of the drawings,reservoir 19 is replaced by a length of the conduit 18 long enough toprovide a reservoir 19:: which is equal in volume to the reservoir 20.This conduit may be curved back and forth in the manner shown for easypositioning between close-set fins of an evaporator coil.

The device of FIGURE 2 also substitutes a diaphragm type actuator 23afor the Sylphon bellows 23 of FIGURE 1. The switch means 11, arm 24,spring 26 and adjusting means 27 are the same as those shown in FIGURE 1and like numerals are used throughout to designate like parts.

The essential difference between the forms of FIGURE 1 and FIGURE 2 isthat the reservoir 19a is connected into series with the reservoir 20a,in FIGURE 2, rather than in parallel, as indicated in FIGURE 1. However,the parts function in :a similar manner to produce the very same result,that is sovaporized fluid from reservoir 19a will pass into reservoir 20and be condensed therein until the portion of the evaporator coil atwhich reservoir 20 is positioned has heated up to the desiredtemperature.

Preferably, conduit 18 connects reservoir 19a to the upper portion ofreservoir 20 in the manner shown in the drawing. Conduit 17 connects thelower portion of the reservoir 20 to the actuator 23a through arestrictive coil 51. With this construction, the actuator 23a, coil 51and conduit 17 are always filled with condensed fluid 14. The

restrictive coil 51 serves to slow down the passage of the fiuid betweenthe reservoir and the actuator 2311. This insures that the fluid inreservoir 20 must be heated above its vaporizing point in order tooperate the actuator and slows down the action sufficiently to preventany sudden surge in pressure, coming from reservoir 19a, from operatingthe actuator 230.

FIGURE 3 illustrates a modified form of the invention in which a singlereservoir 61 is positioned at the coldest part of the evaporator coilduring the defrost cycle, that is near the outlet end of the coil and acheck valve and adjustable orifice unit 62 is interconnected between thereservoir 61 and diaphragm-type actuator 23b.

The unit 62 is shown in some detail in FIGURE 5 of the drawings andconsists essentially of a check Valve 63 and an adjustable orifice 64mounted in a common housing 66. As here shown, the conduit 67 from thereservoir 61 splits into two branches 68 and 69, which communicatethrough passages 71 and 72, formed in housing 66, with branches 73 and74 of a conduit 76 communicating with the actuator 23b. Mounted in anenlargement 77 of passage 71 is a valve member 63 biased toward the seat78 by a spring 79. The arrangement of the valve 63 is such that increasein pressure in the conduit 68, caused by vaporizing of the fluid 14 inreservoir 61, will force the valve member closed. The vapor underpressure will then be forced to pass through conduit 69 and theadjustable orifice 64 in order to reach the actuator 23b.

This will delay the operation of the actuator until the outlet end, andconsequently all of the evaporator coil, has heated up to the desiredtemperature. Adjustment of this time-delay is here provided by a needlevalve 81 movable into the orifice 64 and having an end projectingoutside the housing 66 for manual adjustment thereat.

Rotation of the needle valve 81 to cause it to move to the left, asviewed in FIGURE 5, will tend to close down the orifice 64, furtherrestricting the passage of the vaporized fluid therethrough and thuscreating a longer time-delay. Opening of the valve will, of course, havethe opposite result and will shorten the time-delay.

When the refrigeration cycle is resumed, the reservoir 61 will be cooledsufiiciently to condense the fluid 14 therein. This will create a lowtemperature condition in the conduit 67 and the pressure in conduit 76will force the check valve open, the fluid under pressure passingtherethrough down into the reservoir 61 and operating the actuator toallow the switch means 11 to move to its other terminal position.

The apparatus of FIGURE 4 utilizes a check valve 91 and adjustableorifice 92, similar to that used in the apparatus of FIGURE 3, incombination with reservoirs 19d and 20d located adjacent to the inletand outlet ends of a refrigerator evaporator coil 16a. The reservoirs19d and 20d are interconnected by a conduit 93. Conduits 94 and 95connect the reservoirs 20d and 19d, respectively, to the diaphragm-typeactuator 23d.

The check valve 91 is similar in internal construction to the checkvalve 63 shown in FIGURE 5, and the adjustable restriction device 92 issimilar to the needle valve controlled orifice mounted in that figure.These units may be mounted in the same housing as illustrated in FIGURE5, or may be separated, if desired. In either event, they operate in amanner analogous to that of the unit 62 shown in FIGURE 3.

The adjustable orifice 92 provides a restriction which slows down theoperation of the actuator 23d to prevent sudden surges in pressure fromoperating the switch means 11 prematurely.

In the apparatus of FIGURE 4, it Will be noted that heating up ofreservoir 19d above the vaporizing point of the fluid contained thereinwill cause the vapor to pass through conduit 93 to reservoir 20d whereit will condense until the temperature at the reservoir 20d rises abovethe vaporization point of the liquid. At this time the pressure in theconduit 96 will rise sufliciently to force the vaporized fluid to passthe restriction 92 until sufli'cient pressurized fluid is delivered tothe actuator 23d to operate the same. As the reservoirs 19d and 20d cooldown, the fluid will condense therein creating a localized low-pressurecondition and causing the fluid under pressure to rush from the actuator23d through conduit 94 and check valve 91 back into the reservoir.

The apparatus of FIGURE 6 likewise incorporates a pair of reservoirs 19cand 20e positionable near the inlet and outlet ends, respectively, of anevaporator coil. Reservoirs 1% and 20:: function in a manner similar toreservoirs 19 and 20 of FIGURE 1. When frost accumulates on theevaporator coil adjacent to one of the reservoirs, it lowers thetemperature and causes the vaporizable fluid to condense therein.Heating up of the evaporator coil, as by defrosting, tends to cause thefluid to vaporize within the adjacent reservoir. Thus the action in thereservoirs 1% and 20e proper is the same as the action in the reservoirs19 and 20 of FIGURE 1. However, reservoirs 19c and 20e are not incommunication with each other and the vaporized fluid from one will notcondense in the other. In this, the action of the two reservoirs iscumulative, that is, the arrangement of parts is such that the fluidmust vaporize in each before the actuator 23e will operate.

As may be seen from FIGURE 6, this is accomplished by providing actuator232 with two diaphragms 101 and 102 and mechanically connecting thesediaphragms by means of a member 103. Reservoir 19e communicates throughconduit 104 with a chamber 106 on the upper side of the diaphragm 101,While reservoir 20c communicates through conduit 107 with a chamber 108provided between the diaphragms 101 and 102. The strength of the spring26 is such that pressure must be present in both reservoirs 19c and 202.In this manner, the apparatus will not function to end the defrost cycleuntil the outlet of the evaporator coil adjacent to reservoir 20e haswarmed above the defrost temperature.

The several variations of the system shown and described herein areadapted for uses other than for controlling the defrosting cycle ofrefrigerating apparatus. For example, any of the foregoing systems couldbe applied to the first and last steam radiators in a building heatingsystem, so as to insure that steam would not be cut off until the lastradiator had reached a desired temperature.

With such system of course, the radiators nearer to the source of supplyof steam would use their manually operated valves to preventoverheating.

The present system is adaptable also to uses in smelting or heattreating furnaces and the like where it is necessary to insure that thecoldest portion of the furnace reaches a predetermined temperature, forinstance, the melting point of the material being treated, or theminimum heat treating temperature.

From the foregoing, it will be seen that I have provide a noveltemperature regulating control responsive to variations of temperaturein a body for controlling the supply of heat to such body until theentire body is warmed to a predetermined temperature range.

I claim:

1. A defrosting control for a refrigeration apparatus having acompressor supplying refrigerant to an evaporator coil and a defrosterfor the coil, comprising control means for selectively operating saidcompressor and defroster, a pressure responsive actuator for saidcontrol means, a closed system containing a vaporizable fluid andadapted to be positioned in heat transfer relation to the coil, arestriction in the system formed to slow down the passage of thevaporized fluid from the portion of system at the coil to said actuatorso as to insure that the entire coil reaches a predetermined minimumtemperature before the actuator operates, and a by-pass in said systemaround said restriction and having a check 7 8 valve permitting freeflow of vaporized fluid from the References Cited by the Examineractuator back to the portion of the system at the coil. UNITED STATESPATENTS 2. A defrosting control as defined in claim 12 and 2133966 10/38B h 62 214 wherein said restriction consists of a needle valve formed ucanan X 2,531,136 11/50 Kurtz 62227 X for manual ad ustment fordetermining the time interval 5 2 666 298 1/54 Jones 62*156 necessaryfor sufiicient vaporized fluid to pass therethrough to Operate saidactuator ROBERT A. OLEARY, Primary Examiner.

1. A DEFROSTING CONTROL FOR A REFRIGERATION APPARATUS HAVING ACOMPRESSOR SUPPLYING REFRIGERANT TO AN EVAPORATOR COIL AND A DEFROSTERFOR THE COIL, COMPRISING CONTROL MEANS FOR SELECTIVELY OPERATING SAIDCOMPRESSOR AND DEFROSTER, A PRESSURE RESPONSIVE ACTUATOR FOR SAIDCONTROL MEANS, A CLOSED SYSTEM CONTAINING A VAPORIZABLE FLUID ANDADAPTED TO BE POSITIONED IN HEAT TRANSFER RELATION TO THE COIL, ARESTRICTION IN THE SYSTEM FORMED TO SLOW DOWN THE PASSAGE OF THEVAPORIZED FLUID FROM THE PORTION